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Old 02-08-2010, 10:42 PM
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blackshire blackshire is offline
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Default "Backslider" glider designs

Hello All,

An unusual type of rocket glider (RG) that came up in the thread on break-apart recovery (see: http://www.oldrocketforum.com/showt...63&page=1&pp=10 ) is the "Backslider," a long and narrow rocket that ejects its nose cone (still attached to the rocket body via a shock cord) and glides to Earth backwards (tail-first).

While looking up online information on the rockets built and flown by Dr. Robert H. Goddard (who also noted similar behavior in his L-16 "movable casing rocket"), I came across an illustrated report that Peter Alway and his brother Robert wrote (see: http://www.info-central.org/?article=276 ) about Super Roc Rocket Gliders. In addition to analyzing the design parameters of such tail-first gliding nose-blow recovery rockets, they also investigated similar models that had no moving parts and used asymmetrically-vented ejection charge gases to initiate their tail-first glide mode.

I hope this information will be useful.
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Last edited by blackshire : 02-08-2010 at 10:50 PM. Reason: This ol' hoss done forgot somethin'.
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Old 02-09-2010, 07:40 PM
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IIRC, the Bumbling Brothers essentially concluded that they weren't quite sure why they worked, but were sure they could reliably "glide" as an incredibly easy qualifier in NAR competitions. Mark Fisher subsequently advanced their findings at N46 by getting into why they worked, then tried to propose a couple design attributes that could lead to truly competitive performance for a backslider. His flight tests proved out about half his theories. I'm not sure anyone's done any serious research into it since then (other than at least one I know of that generally argued they should not count as gliders/generate no lift, which has previously been shown to be just plain wrong).

I wound up flying in one meet last year that included a D-RG event, had planned on putting up a nice slide/flop wing but totally trashed the prototype a week before, so decided to try to come up with a semi optimized backslider to fly on 24mm motors. It was a little too windy for my comfort, I had to add some weight for better stability, but it wound up doing respectably, gliding for just under a minute per flight. The biggest problem was just plain seeing it/tracking it (tiny needle in an overcast sky).

Backsliders can certainly come across as almost cheating your way into a decent flight compared to building a nice glider, and I definitely prefer more conventional gliders, but I have to admit, especially when I got into the follow-on research about why they work and how to improve their performance, it really struck me as a fascinating design problem/solution.
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Old 02-10-2010, 12:51 AM
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A small addition that should make them more predictable and improve the glide performance would be a small set of deployable tail surfaces that would flip out near the nose at ejection. This would make a backslider essentially an axisymmetrical standard-configuration glider with an unusually long fuselage! (Guided missiles such as the Sparrow are powered airplanes of this type, and missiles like the Sidewinder are axisymmetrical tandem-wing or canard airplanes.)
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Old 02-10-2010, 03:26 AM
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Quote:
Originally Posted by chanstevens
I wound up flying in one meet last year that included a D-RG event, had planned on putting up a nice slide/flop wing but totally trashed the prototype ...
Chan, your experience reminds me of a great story about those Alway boys and their backslider.

My daughter built her first B Rocket Glider for a local meet several years ago. It was a nice Edmonds kit that re-kitted itself half way up the launch rod (not Rob's fault, ours).

The Alway brothers were at the meet and Bob saw my daughter's disappointment. So he came over and asked my daughter if she had a second glider to fly. When she answered "no", Bob said he could help her build a different kind of glider if she was interested. He then walked her through the process of building a backslider and explained the whole concept to her. They cut the wing of her broken glider into 3 fins, Bob provided a couple lengths of 18mm tubing and a coupler, and Peter provided a nosecone and a paper punch. My daughter superglued the whole thing together and got a great gliding flight out of it to her complete delight. Afterwards she had Pete and Bob autograph it for her (Peter included the patent number next to his signature ).

Those Alway boys aren't just smart, they're wonderful teachers and friends.
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Old 02-10-2010, 11:24 AM
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Quote:
Originally Posted by Gus
Chan, your experience reminds me of a great story about those Alway boys and their backslider.

My daughter built her first B Rocket Glider for a local meet several years ago. It was a nice Edmonds kit that re-kitted itself half way up the launch rod (not Rob's fault, ours).

The Alway brothers were at the meet and Bob saw my daughter's disappointment. So he came over and asked my daughter if she had a second glider to fly. When she answered "no", Bob said he could help her build a different kind of glider if she was interested. He then walked her through the process of building a backslider and explained the whole concept to her. They cut the wing of her broken glider into 3 fins, Bob provided a couple lengths of 18mm tubing and a coupler, and Peter provided a nosecone and a paper punch. My daughter superglued the whole thing together and got a great gliding flight out of it to her complete delight. Afterwards she had Pete and Bob autograph it for her (Peter included the patent number next to his signature ).

Those Alway boys aren't just smart, they're wonderful teachers and friends.


The info on the backsliding gliders has been wonderful but its stories like this one, and a few experiences, that really make me thankful.
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Old 02-10-2010, 07:52 PM
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Quote:
Originally Posted by JAL3
The info on the backsliding gliders has been wonderful but its stories like this one, and a few experiences, that really make me thankful.
Yes, the co-operation even in the midst of competition has always endeared me to model rocketry.
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http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
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Old 02-10-2010, 08:04 PM
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Powered backslider rockets were also considered for Mars missions. The original Estes Mars Snooper was one such design, and it was not a fictitious one (see: http://www.plan59.com/av/av254.htm ). It was a 1950s design proposal for a nuclear rocket powered spaceship that would also have been capable of flying backwards through Mar's atmosphere as a nuclear ramjet powered airplane.

I first saw a painting and description of it in an old late 1950s book on full-scale rocketry (whose name I unfortunately can't remember), and the Mars Snooper's design was also familiar enough that it appeared in "The Last Martian's Story" (a short story in an early 1960s elementary school reading book) as the "Martian Princess," a Mars shuttle spaceship. For atmospheric flight, the Mars Snooper's rear rocket nozzle would have served as an air intake, and the large rear fins would have provided lift as wings. The forward canards would have acted as tail surfaces. The Estes Mars Snooper and Mars Snooper II kits might make good backslider rocket gliders.
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Last edited by blackshire : 02-10-2010 at 08:31 PM. Reason: This ol' hoss done forgot somethin'.
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Old 02-10-2010, 08:27 PM
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Quote:
Originally Posted by Gus
Chan, your experience reminds me of a great story about those Alway boys and their backslider.

My daughter built her first B Rocket Glider for a local meet several years ago. It was a nice Edmonds kit that re-kitted itself half way up the launch rod (not Rob's fault, ours).

The Alway brothers were at the meet and Bob saw my daughter's disappointment. So he came over and asked my daughter if she had a second glider to fly. When she answered "no", Bob said he could help her build a different kind of glider if she was interested. He then walked her through the process of building a backslider and explained the whole concept to her. They cut the wing of her broken glider into 3 fins, Bob provided a couple lengths of 18mm tubing and a coupler, and Peter provided a nosecone and a paper punch. My daughter superglued the whole thing together and got a great gliding flight out of it to her complete delight. Afterwards she had Pete and Bob autograph it for her (Peter included the patent number next to his signature ).

Those Alway boys aren't just smart, they're wonderful teachers and friends.


And as further evidence that karma exists, I have vivid memories of Peter Alway doing his thermal dance at NARAM 47 and flying an Edmonds Deltie glider just to get a qualified flight in on A-BG. He did indeed catch a thermal, one of the strongest I've ever seen on that field (my home field), and it literally spiraled off out of sight directly over the launch pads after something like 14 minutes, ridiculously out in front of the second highest team score.
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Old 02-10-2010, 08:40 PM
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Quote:
Originally Posted by chanstevens
And as further evidence that karma exists, I have vivid memories of Peter Alway doing his thermal dance at NARAM 47 and flying an Edmonds Deltie glider just to get a qualified flight in on A-BG. He did indeed catch a thermal, one of the strongest I've ever seen on that field (my home field), and it literally spiraled off out of sight directly over the launch pads after something like 14 minutes, ridiculously out in front of the second highest team score.
Not karma--Aeolus! :-)
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR
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Old 02-10-2010, 11:59 PM
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I pulled the signed backslider out of storage and took a couple of pics (kinda hard to do with such a long rocket). Turns out it must have been A-Rocket Glide because the tube is 13mm, not 18. Very cool rocket. Note the made-on-scene not-sanded fins and the taped on launch lug. The exhaust port is on the back side.
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